Photovoltaic module

Abstract

This invention provides a photovoltaic module that suppresses variations in quality and achieves a high light confinement effect. [Solution] The photovoltaic module 1 is generally configured to include a substrate unit 2 having a substrate 20 with an uneven surface 205 consisting of a plurality of peaks 203 and a plurality of valleys 204, and a filling portion 21 that fills the uneven surface 205 so that the surface 210 becomes flat and transmits light 9, and a transparent electrode 3 provided on the substrate unit 2 that transmits light 9. This photovoltaic module 1 can suppress variations in quality and obtain a high light confinement effect.

Description

Technical Field

[0001] The present invention relates to a photovoltaic module.

Background Art

[0002] As a conventional technique, a method for manufacturing a transparent conductive substrate for a solar cell is known in which a curable resin is applied on a transparent support substrate, the curable resin is cured while pressing a mold, and then the mold is removed to laminate a cured resin layer having irregularities formed on the transparent support substrate (see, for example, Patent Document 1).

[0003] In this method for manufacturing a transparent conductive substrate for a solar cell, a transparent conductive layer is laminated on the cured resin layer so that the shape of the irregularities formed on the surface of the cured resin layer is maintained, and a transparent conductive substrate for a solar cell including a transparent support substrate, a cured resin layer, and a transparent conductive layer can be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional transparent conductive substrate for a solar cell, since a transparent conductive layer is laminated on the irregularities of a cured resin layer, there is a problem that the applied electrode material accumulates in the valley portions of the irregularities or the electrode material does not sufficiently cover the peak portions of the irregularities, resulting in variations in the quality of the transparent conductive layer.

[0006] Therefore, an object of the present invention is to provide a photovoltaic module capable of suppressing variations in quality and obtaining a high light confinement effect.

Means for Solving the Problems

[0007] One aspect of the present invention provides a photovoltaic module comprising a substrate having an uneven surface consisting of a plurality of peaks and a plurality of valleys, a light-transmitting substrate unit having a filling portion that fills the uneven surface and makes the surface flat, and a light-transmitting transparent electrode provided on the substrate unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress variations in quality and obtain a high light confinement effect. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an example of a cross-sectional view of a photovoltaic module according to the first embodiment, obtained by cutting along line AA in Figure 2, as seen from the direction of the arrow. [Figure 2] Figure 2 is a perspective view showing an example of the uneven surface of the substrate of a photovoltaic module according to the first embodiment. [Figure 3] Figure 3(a) is an example of a cross-sectional view of the substrate portion in a cross-section cut along line AA in Figure 2 of a photovoltaic module according to the first embodiment, and Figure 3(b) is an example of a cross-sectional view of the transparent conductive film portion in a cross-section cut along line AA in Figure 2. [Figure 4] Figures 4(a) and 4(b) show examples of uneven surfaces on the substrate of a modified photovoltaic module. [Figure 5] Figures 5(a) and 5(b) show examples of uneven surfaces on the substrate of a modified photovoltaic module. [Figure 6] Figures 6(a) to 6(d) show an example of a method for manufacturing a photovoltaic module according to the first embodiment. [Figure 7] Figures 7(a) and 7(b) show an example of a method for manufacturing a photovoltaic module according to the first embodiment. [Figure 8] Figure 8 is an example of a cross-sectional view of a photovoltaic module according to the second embodiment. [Figure 9] Figure 9 is an example of a cross-sectional view of a photovoltaic module according to the third embodiment. [Figure 10] FIG. 10 is an example of a cross-sectional view of a photovoltaic module according to the fourth embodiment. [Figure 11] FIG. 11(a) is a cross-sectional view showing an example of a photovoltaic module according to the fifth embodiment, and FIG. 11(b) is a cross-sectional view showing an example of a photovoltaic module according to a modified example. [Figure 12] FIGS. 12(a) to 12(c) are diagrams showing an example of a manufacturing method of a photovoltaic module according to the fifth embodiment. **[Embodiments for Carrying Out the Invention]**

[0010] (Summary of the Embodiment) The photovoltaic module according to the embodiment has a substrate having concavo-convex portions composed of a plurality of ridges and a plurality of valleys, and a filling portion filled in the concavo-convex portions and having a flat surface, and is schematically configured to include a substrate unit that transmits light, and a transparent electrode provided on the substrate unit and transmitting light.

[0011] <00078>

[0012] [First Embodiment] (Outline of Photovoltaic Module 1) FIG. 1 is an example of a cross-sectional view of a photovoltaic module according to the first embodiment as seen from the arrow direction of a cross-section cut along line A-A in FIG. 2. FIG. 2 is a perspective view showing an example of the concavo-convex portions of the substrate of the photovoltaic module according to the first embodiment. FIG. 3(a) is an example of a cross-sectional view of the substrate portion in the cross-section cut along line A-A of the photovoltaic module according to the first embodiment, and FIG. 3(b) is an example of a cross-sectional view of the transparent conductive film portion in the cross-section cut along line A-A of FIG. 2.

[0013] In each of the figures related to the embodiments described below, the ratios and shapes between the figures may differ from the actual ratios and shapes. Also, "A~B" indicating a numerical range is used to mean A or more and B or less. Hereinafter, the outline of the photovoltaic module 1 will be described.

[0014] As shown in FIGS. 1 to 3(a), the photovoltaic module 1 includes a substrate 20 having a concavo-convex portion 205 composed of a plurality of peak portions 203 and a plurality of valley portions 204, and a filling portion 21 filled in the concavo-convex portion 205 and having a flat surface 210, and a substrate unit 2 that transmits light 9, and a transparent electrode 3 provided on the substrate unit 2 and transmitting light 9, and is schematically configured.

[0015] As shown in FIG. 1, the substrate unit 2 has an upper substrate 22 disposed on the filling portion 21. The transparent electrode 3 is provided on the upper substrate 22.

[0016] As shown in FIG. 1, the transparent electrode 3 is composed of a transparent conductive film 30 and a transparent electrode film 31. The transparent conductive film 30 has an electrode concavo-convex portion 305 composed of a plurality of electrode peak portions 303 and a plurality of electrode valley portions 304.

[0017] The filling portion 21 is configured to bond the substrate 20 and the upper substrate 22.

[0018] The photovoltaic module 1 is an organic solar cell, a silicon solar cell, a compound solar cell, an organic-inorganic hybrid solar cell, or the like. The photovoltaic module 1 of the present embodiment is, for example, a perovskite solar cell. The peak portions 203 and valley portions 204 of the substrate 20 and the electrode peak portions 303 and electrode valley portions 304 of the transparent conductive film 30 are provided continuously and alternately or randomly as shown in FIG. 1.

[0019] As an example, the photovoltaic module 1 of this embodiment is generally configured to include a substrate unit 2, a transparent electrode 3 provided on the substrate unit 2, a photoelectric conversion layer 4 provided on the transparent electrode 3 and converting the light energy of light 9 incident from the back surface 201 of the substrate unit 2 into electrical energy, and an upper electrode 5 provided on the photoelectric conversion layer 4, as shown in Figure 1. At least the transparent electrode 3, the photoelectric conversion layer 4, and the upper electrode 5 of the photovoltaic module 1 are sealed. As an example, the photovoltaic module 1 may also be configured to include multiple photovoltaic elements, each consisting of at least the transparent electrode 3, the photoelectric conversion layer 4, and the upper electrode 5.

[0020] As shown in Figure 3(a), the uneven portion 205 of the substrate 20 has curvature at least one of the highest point of the peak portion 203, which is the vertex 203a, and the lowest point of the valley portion 204, which is the base point 204a.

[0021] Furthermore, the ridge line 206 shown in Figure 3(a) is a curve that passes through the vertex 203a of the peak 203 and the base point 204a of the valley 204, and connects the outer shape of the cross-section obtained by cutting with a plane perpendicular to the surface 200 of the substrate 20.

[0022] As an example, the peaks 203 and valleys 204 are separated by the reference plane 202 of the substrate 20, as shown in Figure 3(a). The ridge line 206 is, as an example, a curve formed by connecting the peak ridge line 206a of the peak 203 and the valley ridge line 206b of the valley 204. The reference plane 202 is, as an example, a plane that includes the center heights of the peaks 203 and valleys 204 and is parallel to the surface 200 of the substrate 20 before processing. The center height in this embodiment is, as an example, the height at which the first distance L1 from the reference plane 202 to the apex 203a of the peak 203 and the second distance L2 from the reference plane 202 to the bottom point 204a of the valley 204 are equal. The center height can be determined using, for example, an arithmetic mean or a weighted mean if there is variation in the heights of the peaks 203 and valleys 204.

[0023] In this embodiment, the uneven surface 205 is, for example, tangentially continuous at its ridges 206. This tangential continuity means that the tangents at the endpoint 207 where the peak ridge 206a and the valley ridge 206b connect coincide. In other words, tangential continuity means that the differential value at endpoint 207 of the peak ridge 206a and the differential value at endpoint 207 of the valley ridge 206b coincide. By adopting this configuration, the substrate 20 can obtain a high light confinement effect 9.

[0024] As shown in Figure 3(b), the electrode uneven portion 305 of the transparent conductive film 30 has curvature at least one of the highest point of the electrode peak portion 303, which is the apex 303a, and the lowest point of the electrode valley portion 304, which is the base point 304a.

[0025] Furthermore, the ridge line 306 shown in Figure 3(b) is a curve connecting the outer edges of the cross-section of the transparent conductive film 30 shown in Figure 1.

[0026] The electrode peaks 303 and electrode valleys 304 are separated by a reference plane 302 of the transparent conductive film 30, as shown in Figure 3(b) as an example. The ridge line 306 is, as an example, a curve formed by connecting the ridge line 306a of the electrode peak 303 and the ridge line 306b of the electrode valley 304. The reference plane 302 is, as an example, a plane defined to include the center heights of the electrode peaks 303 and electrode valleys 304. The center height in this embodiment is, as an example, the height at which the third distance L3 from the reference plane 302 to the apex 303a of the electrode peak 303 is equal to the fourth distance L4 from the reference plane 302 to the bottom point 304a of the electrode valley 304. The center height can be determined using, for example, an arithmetic mean or a weighted mean if there is variation in the heights of the electrode peaks 303 and electrode valleys 304.

[0027] In this embodiment, the electrode surface 305 is, for example, tangentially continuous at its ridges 306. This tangential continuity means that the tangents at the endpoint 307 where the peak ridge 306a and the valley ridge 306b connect coincide. In other words, tangential continuity means that the differential value at endpoint 307 of the peak ridge 306a and the differential value at endpoint 307 of the valley ridge 306b coincide. By adopting this configuration, the transparent conductive film 30 can obtain a high light confinement effect 9.

[0028] (Configuration of circuit board unit 2) The substrate 20 of the substrate unit 2 is, for example, a substrate formed using a transparent resin material such as acrylic, PET (Polyethylene Terephthalate), polycarbonate, polyethersulfone, fluorine film, or triacetate, but is not limited thereto. The substrate 20 in this embodiment is a film substrate using PET, which has excellent flexibility and high transparency. The substrate 20 may, for example, be made more easily deformable at the top than at the bottom.

[0029] The substrate 20 has a thickness of 200 to 700 μm, for example. In this embodiment, the substrate 20 has a thickness of 300 μm, for example. The substrate 20 may also have a configuration in which multiple layers are stacked. The substrate 20 may have uneven surfaces 205 formed by transferring the uneven shape of a mold, for example, or by blowing particulate powder onto the surface 200 to form the uneven surfaces 205.

[0030] The filling portion 21 is formed using a highly fluid, transparent resin material. Examples of such highly fluid resin materials include acrylic and PET. The filling portion 21 is filled into the valleys 204 of the uneven portions 205 of the substrate 20, so that the surface 210 becomes flat. The filling portion 21 adheres and integrates the substrate 20 and the upper substrate 22.

[0031] The upper substrate 22 is a thin film formed using a transparent resin material such as acrylic or PET. This upper substrate 22 has a thickness of 10 to 500 μm, preferably 30 μm. The upper substrate 22 has a flat surface 220, which forms the surface of the substrate unit 2. The upper substrate 22 may be composed of multiple layers, for example.

[0032] (Configuration of transparent electrode 3) The transparent conductive film 30 of the transparent electrode 3 is formed from a substantially transparent transparent conductive oxide (TCO) to allow light 9 incident from the substrate 20 side to be incident on the photoelectric conversion layer 4, as shown in Figure 1, for example. Such conductive materials include metal oxides, transparent conductive polymers, transparent conductive inks, and transparent conductive glass (FTO: Fluorine-doped tin oxide). Metal oxides include, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), and titanium oxide (TiO2), which extract the current generated in the photoelectric conversion layer 4. Transparent conductive polymers include, for example, PEDOT / PSS (poly-3,4-ethylenedioxythiophene / polysulfonic acid). Transparent conductive inks include, for example, those containing carbon nanotubes and silver nanofibers in the binder.

[0033] The transparent conductive film 30 in this embodiment is, for example, a conductive film made of indium tin oxide (ITO), but is not limited thereto. The transparent conductive film 30 is formed by, for example, blowing particulate powder onto the surface 300 to form the electrode uneven portion 305. The transparent conductive film 30 may also be formed on the upper part of the electrode uneven portion 305 using, for example, a vacuum deposition method.

[0034] As shown in Figures 1 and 3(b), the transparent conductive film 30 has a surface 300 with an uneven shape due to the electrode uneven portion 305, and a back surface 301 that is flat and provided on the surface 220 of the substrate unit 2.

[0035] If a transparent electrode film 31 is present, it may be formed using the same material as the transparent conductive film 30, for example. Alternatively, an electron transport layer may be formed adjacent to the photoelectric conversion layer 4, in which case the transparent electrode film 31 may be made of, for example, TiO2 or SnO2. This transparent electrode film 31 is formed along the electrode peaks 303 and electrode valleys 304 of the transparent conductive film 30.

[0036] The transparent electrode film 31 has a thickness of, for example, 0.05 to 1.0 μm, and preferably 0.5 μm.

[0037] (Configuration of the photoelectric conversion layer 4) As described above, the photoelectric conversion layer 4 is configured to convert the light energy of the light 9 incident from the substrate 20 side into electrical energy.

[0038] (Configuration of upper electrode 5) The upper electrode 5 is formed from a conductive material such as gold, silver, aluminum, and copper, and is used not only to extract holes or electrons generated in the photoelectric conversion layer 4, but also to reflect incident light back to the photoelectric conversion layer 4 to obtain a light confinement effect. The upper electrode 5 is formed from gold as an example, but is not limited to this. For example, when light is taken in from the upper electrode 5 side, this upper electrode 5 may be configured as a transparent electrode.

[0039] (Regarding the uneven portion 205 of the substrate 20) As shown in Figure 3(a), the distance between the mountain section 203 and the valley section 204 is the sum of the first distance L1 from the vertex 203a of the adjacent mountain section 203 to the reference plane 202 and the second distance L2 from the base point 204a of the valley section 204 to the reference plane 202. a It is within a predetermined distance range.

[0040] This distance range is, for example, 0.2 to 5.0 μm, and more preferably 0.3 to 1.2 μm. In this embodiment, the peaks 203 and valleys 204 are 0.3 μm ≤ L1 + L2 ≤ 1.2 μm. The distance range is such that if there is no variation in the distances of the peaks 203 and valleys 204 from the reference plane 202, and the first distance L1 and the second distance L2 are equal, the distance between the vertex 203a and the base point 204a will be 2L1 or 2L2. a You could intentionally create variations, for example, around 10 different types.

[0041] Furthermore, as shown in Figure 3(a), the first interval P1 between the vertices 203a of adjacent peaks 203 and the second interval P2 between the base points 204a of adjacent valleys 204 are both within a predetermined interval range.

[0042] This spacing range is, for example, 0.2 to 6.0 μm, and more preferably 0.3 to 1.2 μm. In this embodiment, for example, the first spacing P1 and the second spacing P2 are equal. Note that variations in spacing, for example, around 10 different values, may be intentionally created.

[0043] Furthermore, it is preferable that the number obtained by dividing the height (L1+L2) of adjacent peaks 203 and valleys 204 by the width of the peaks 203 (second spacing P2) and the width of the valleys 204 (first spacing P1) is less than 1. In other words, the uneven portion 205 is formed such that, for example, at least one of [(L1+L2) / P1]<1 and [(L1+L2) / P2]<1 holds true.

[0044] (Regarding the electrode uneven portion 305 of the transparent conductive film 30) As shown in Figure 3(b), the distance between the electrode peak 303 and the electrode valley 304 is the sum of the third distance L3 and the fourth distance L4. b It is within a predetermined distance range.

[0045] This distance range is, for example, 0.2 to 5.0 μm, and more preferably 0.3 to 1.2 μm. In this embodiment, the distance between the electrode peak 303 and the electrode valley 304 is 0.3 μm ≤ L3 + L4 ≤ 1.2 μm. The distance range is such that when there is no variation in the distances of the electrode peak 303 and the electrode valley 304 from the reference plane 302, and the third distance L3 and the fourth distance L4 are equal, the distance between the vertex 303a and the base point 304a is 2L3 or 2L4. b You could intentionally create variations, for example, around 10 different types.

[0046] Furthermore, as shown in Figure 3(b), the third interval P3 and the fourth interval P4 of the electrode peaks 303 and electrode valleys 304 are both within a predetermined interval range.

[0047] This spacing range is, for example, 0.2 to 6.0 μm, and more preferably 0.3 to 1.2 μm. In this embodiment, for example, the third spacing P3 and the fourth spacing P4 are equal. Note that variations in spacing, for example, around 10 different values, may be intentionally created.

[0048] Furthermore, it is preferable that the electrode uneven portion 305 is formed such that the number obtained by dividing the height (L3+L4) of adjacent electrode peaks 303 and electrode valleys 304 by the width of the electrode peaks 303 (fourth spacing P4) and the width of the electrode valleys 304 (third spacing P3) is less than 1. In other words, the electrode uneven portion 305 is formed such that, for example, at least one of [(L3+L4) / P3]<1 and [(L3+L4) / P4]<1 holds true.

[0049] In this case, it is preferable that the vertices 203a of the uneven portion 205 of the substrate 20 coincide with the vertices 303a of the electrode uneven portion 305 of the transparent conductive film 30, and the base points 204a of the uneven portion 205 of the substrate 20 coincide with the base points 304a of the electrode uneven portion 305. In this case, the first spacing P1 becomes equal to the third spacing P3, and the second spacing P2 becomes equal to the fourth spacing P4.

[0050] (Regarding variations) Figures 4(a) to 5(b) show examples of the uneven surface of the substrate of a modified photovoltaic module. In the following description, a modified example of the uneven surface 205 of the substrate 20 will be explained, but the same applies to the electrode uneven surface 305 of the transparent conductive film 30.

[0051] Figure 4(a) shows a modified example in which, as an example, at least a portion of the first distance L1 from the vertex 203a of the peak section 203 to the reference plane 202 is different, at least a portion of the second distance L2 from the base point 204a of the valley section 204 to the reference plane 202 is different, and the first interval P1 between the vertices 203a and the second interval P2 between the base points 204a are the same. The first distance L1 varies from vertex 203a to vertex 203a. The second distance L2 also varies from base point 204a to base point 204a. This variation indicates a state in which both identical and different distances are mixed. Note that the base point 204a does not have curvature.

[0052] Figure 4(b) shows a modified example in which the first distance L1 and the second distance L2 are the same, and the first interval P1 and the second interval P2 vary. The first interval P1 varies for each adjacent vertex 203a. The second interval P2 varies for each adjacent base point 204a. Note that the base point 204a does not have curvature.

[0053] Figure 5(a) shows a modified example in which at least a portion of the first distance L1 differs, at least a portion of the second distance L2 differs, and the first interval P1 and the second interval P2 are the same. The first distance L1 varies from vertex 203a to vertex 203a. The second distance L2 also varies from base point 204a to base point 204a. Note that vertex 203a and base point 204a do not have curvature.

[0054] Figure 5(b) shows, as an example, a modified example in which the first distance L1 and the second distance L2 are the same, and at least a portion of the first interval P1 and at least a portion of the second interval P2 are different. The first interval P1 varies for each adjacent vertex 203a. The second interval P2 varies for each adjacent base point 204a. Note that vertices 203a and base points 204a do not have curvature.

[0055] Furthermore, the photovoltaic module 1 may be constructed by combining the above embodiments and modified examples, with respect to the uneven portion 205 of the substrate 20 and the electrode uneven portion 305 of the transparent conductive film 30.

[0056] (Manufacturing method for photovoltaic module 1) An example of a method for manufacturing the photovoltaic module 1 of this embodiment will be described below with reference to Figures 6(a) to 7(b).

[0057] As shown in Figure 6(a), a substrate 20 having a bumpy portion 205 is prepared. This substrate 20 is formed by, for example, pressing a mold having a bumpy shape onto the surface 200 of the substrate 20 and transferring the bumpy shape of the mold, thereby forming a bumpy portion 205 consisting of a plurality of peaks 203 and a plurality of valleys 204.

[0058] Next, as shown in Figure 6(b), the uneven portion 205 is filled and the resin is filled so that the surface 210 becomes flat, thereby forming the filled portion 21. The filled portion 21 is formed, for example, by pouring molten resin onto the substrate 20.

[0059] Next, as shown in Figure 6(c), the upper substrate 22 is attached to the filling portion 21 to form the substrate unit 2.

[0060] Next, as shown in Figure 6(d), a transparent conductive film 30 having electrode irregularities 305 is formed on the substrate unit 2. The transparent conductive film 30 is formed, for example, by vacuum deposition or spin coating.

[0061] Next, as shown in Figure 7(a), a transparent electrode film 31 is formed along the uneven shape of the electrode surface 305 to form the transparent electrode 3. The transparent electrode film 31 is formed, for example, by vacuum deposition or spin coating.

[0062] Next, as shown in Figure 7(b), a photoelectric conversion layer 4 is formed on the transparent electrode 3. Subsequently, an upper electrode 5 and other components are formed on the photoelectric conversion layer 4 to obtain the photovoltaic module 1.

[0063] (Effects of the first embodiment) The photovoltaic module 1 according to this embodiment can suppress variations in quality and achieve a high light confinement effect. Specifically, in a photovoltaic module where transparent electrodes are directly placed on an uneven surface, variations in quality may occur, such as voids forming in the valleys of the uneven surface due to insufficient filling of the transparent electrode material, or insufficient film thickness being obtained due to the material dripping from the peaks. However, in the photovoltaic module 1, transparent electrodes 3 are provided on a substrate unit 2 consisting of a filling section 21 that fills the uneven surface 205 of the substrate 20 to make the surface 210 flat, and an upper substrate 22 provided on the filling section 21 with a surface 220 that is flat. As a result, the above-mentioned variations in quality are suppressed, and a high light confinement effect can be obtained.

[0064] The photovoltaic module 1 can achieve a high light confinement effect through the substrate unit 2 and the transparent electrode 3, thereby improving the conversion efficiency of converting light energy into electrical energy compared to cases where only one of these components is provided.

[0065] Since the surface 220 of the substrate unit 2 of the photovoltaic module 1 is flat, compared to the case where transparent electrodes are formed on an uneven surface, a general manufacturing method for forming transparent electrodes 3 on a flat surface can be used instead of a special manufacturing method that enables high-precision film deposition on an uneven surface, thereby reducing manufacturing costs.

[0066] Since the photovoltaic module 1 does not have sharp edges on the ridges 206 of the uneven portion 205 and the ridges 306 of the electrode uneven portion 305, defects are less likely to occur in the uneven portion 205 and the electrode uneven portion 305 compared to a configuration that does not employ this design, and a high light confinement effect and incident light efficiency can be obtained.

[0067] The photovoltaic module 1 has a distance L which is the sum of a first distance L1 and a second distance L2 on the substrate 20. a , and the distance L, which is the sum of the third distance L3 and the fourth distance L4 of the transparent conductive film 30. b Since the distance range has deliberately regular variations, and the first spacing P1 and the second spacing P2 of the substrate 20, and the third spacing P3 and the fourth spacing P4 of the transparent conductive film 30 also have deliberately regular variations within the spacing range, a stable and high conversion efficiency can be obtained even if deviations occur, compared to when this configuration is not adopted. In addition, the photovoltaic module 1 deliberately has multiple distances L a distance L b Since the first interval P1 to the fourth interval P4 are set, the overall manufacturing can be carried out with higher precision and stability compared to when this configuration is not adopted.

[0068] [Second Embodiment] The second embodiment differs from the first embodiment in that it does not include an upper substrate.

[0069] Figure 8 is an example of a cross-sectional view of a photovoltaic module according to the second embodiment. Figure 8 is an example of a cross-sectional view cut at the location corresponding to Figure 1 of the first embodiment. In the embodiments described below, parts having the same function and configuration as the first embodiment will be denoted by the same reference numerals as in the first embodiment, and their descriptions will be omitted.

[0070] As shown in Figure 8, the photovoltaic module 1 of this embodiment is generally configured to include a substrate unit 2 that transmits light 9 and has a substrate 20 having an uneven surface 205 consisting of a plurality of peaks 203 and a plurality of valleys 204, and a filling portion 21 that fills the uneven surface 205 so that the surface 210 is flat, and a transparent electrode 3 that transmits light 9 and is provided on the substrate unit 2. The transparent electrode 3 of this embodiment is provided on the surface 210 of the filling portion 21.

[0071] (Effects of the second embodiment) In this embodiment, the photovoltaic module 1 has the transparent electrode 3 placed on the flat surface 210 of the filled portion 21, which makes it easier to form the transparent electrode 3 compared to the case where the transparent electrode is placed on an uneven surface.

[0072] [Third Embodiment] The third embodiment differs from the other embodiments in that the surface of the transparent electrode film is planar.

[0073] Figure 9 is an example of a cross-sectional view of a photovoltaic module according to the third embodiment. Figure 9 is an example of a cross-sectional view cut at the location corresponding to Figure 1 of the first embodiment.

[0074] In this embodiment, the transparent electrode film 31 is not provided along the electrode uneven portion 305 of the transparent conductive film 30, but rather the electrode uneven portion 305 is filled so that the surface 310 is flat. The photoelectric conversion layer 4 is provided on the flat surface 310 of the transparent electrode film 31.

[0075] (Effects of the third embodiment) In this embodiment, the photovoltaic module 1 has a flat surface 310 of the transparent electrode film 31, which allows for easier formation of the photoelectric conversion layer 4 compared to the case where it is provided along the uneven surface of the electrode.

[0076] [Fourth Embodiment] The fourth embodiment differs from the above embodiment in that the spacing between the uneven portion of the substrate and the electrode uneven portion of the transparent conductive film is different.

[0077] Figure 10 is an example of a cross-sectional view of a photovoltaic module according to the fourth embodiment. Figure 10 is an example of a cross-sectional view cut at the location corresponding to Figure 1 of the first embodiment.

[0078] In this embodiment, the photovoltaic module 1 has a first spacing P1 between the peaks 203 of the substrate 20 and a third spacing P3 between the electrode peaks 303 of the transparent conductive film 30, and the second spacing P2 between the valleys 204 and the fourth spacing P4 between the electrode valleys 304 are different.

[0079] As a modified example, in the photovoltaic module 1, the first spacing P1 of the peaks 203 and the third spacing P3 of the electrode peaks 303, and the second spacing P2 of the valleys 204 and the fourth spacing P4 of the electrode valleys 304 may be the same, while the vertices 203a of the peaks 203 and the vertices 303a of the electrode peaks 303a, and the base points 204a of the valleys 204 and the base points 304a of the electrode valleys 304 may be misaligned.

[0080] (Effects of the fourth embodiment) In this embodiment, the photovoltaic module 1 has different spacings: the first spacing P1 of the peaks 203 of the substrate 20 and the third spacing P3 of the electrode peaks 303 of the transparent conductive film 30, and the second spacing P2 of the valleys 204 and the fourth spacing P4 of the electrode valleys 304. Compared to a configuration that does not employ this setup, the degree of freedom of the uneven surfaces 205 of the substrate 20 and the electrode uneven surfaces 305 of the transparent conductive film 30 is improved.

[0081] [Fifth Embodiment] The fifth embodiment differs from the other embodiments in that the filling portion is formed by transparent particles.

[0082] Figure 11(a) is a cross-sectional view showing an example of a photovoltaic module in which the filling portion is made of particles according to the fifth embodiment, and Figure 11(b) is a cross-sectional view showing an example of a photovoltaic module according to a modified example.

[0083] As shown in Figure 11(a), the photovoltaic module 1 of this embodiment has a filling section 21 composed of a plurality of transparent particles 211. These particles 211 are conductive and have a refractive index close to that of the transparent electrode 3. When the transparent electrode 3 is ITO, the refractive index is approximately 2.0. Therefore, for example, when the transparent electrode 3 is ITO, the refractive index of the particles 211 is preferably 1.8 to 2.2, and more preferably 2.0 to 2.1.

[0084] The particles 211 in this embodiment are formed using ITO, since the transparent electrode 3 is ITO. For example, the primary particle size (D50) of the particles 211 is 5 to 20 nm. The particles 211 are not limited to ITO; they can be made of a material with a similar refractive index to the transparent electrode 3, such as titanium, aluminum oxide, conductive and non-conductive resins.

[0085] The particles 211 are dissolved in a solvent, for example, and applied to the substrate 20 using a spin coating method or a drop casting method. This solvent is, for example, acetone or ethanol, but is not limited to these. In this embodiment, the solvent is, as an example, acetone, which has low viscosity and can fill the particles 211 up to the bottom point 204a of the valleys 204 of the substrate 20.

[0086] The particles 211 coated on the substrate 20 are subjected to an annealing treatment. This annealing treatment is performed, for example, at 150°C for 90 minutes, but is not limited to this. This annealing treatment evaporates the solvent and sintersects the contact areas between the particles, thereby improving electrical conductivity.

[0087] As shown in Figure 11(a), the particle 211 is formed by the spin coating method, higher than the peak 203a of the peak 203 of the substrate 20.

[0088] As a variation, the filling portion 21 may be formed lower than the peak 203a of the peak 203, as shown in Figure 11(b). The surface 210 of this filling portion 21 is lower than the peak 203a of the peak 203 of the substrate 20, as shown in Figure 11(b).

[0089] Below, an example of a method for manufacturing the photovoltaic module 1 of this embodiment will be described with reference to Figures 12(a) to 12(c).

[0090] (Manufacturing method for photovoltaic module 1) As shown in Figure 12(a), a substrate 20 having an uneven surface 205 is prepared.

[0091] Next, as shown in Figure 12(b), multiple particles 211 are applied to the uneven portion 205, and an annealing treatment is performed to form the filled portion 21.

[0092] Next, as shown in Figure 12(c), a transparent electrode 3 is formed on the filled portion 21.

[0093] Next, a photoelectric conversion layer 4 is formed on the transparent electrode 3, and an upper electrode 5 and the like are formed on the photoelectric conversion layer 4 to obtain a photovoltaic module 1.

[0094] (Effects of the fifth embodiment) In this embodiment, the photovoltaic module 1 has a filling section 21 composed of multiple transparent particles 211. Compared to a configuration that is not adopted, the filling rate of the particles 211 into the uneven section 205 is improved, and a higher light confinement effect can be obtained.

[0095] Since the photovoltaic module 1 forms the filling portion 21 using particles 211 with a refractive index close to that of the transparent electrode 3, it is possible to form a filling portion 21 as a transparent electrode film that is thinner and more efficiently fills the valleys 204 of the uneven portion 205 compared to when this configuration is not adopted.

[0096] The surface 210 of the filled portion 21, which is obtained by filling it with multiple transparent particles 211, has a high resistance value. Therefore, when a photoelectric conversion layer 4 is formed on this filled portion 21, the resistance value between it and the photoelectric conversion layer 4 increases, reducing the conversion efficiency. However, in the photovoltaic module 1, a transparent electrode 3 is formed on the filled portion 21 by sputtering. Compared to a configuration that does not employ this method, the resistance value between the filled portion 21 and the transparent electrode 3, which are made of the same material, is lower, and the resistance value of the surface 300 of the transparent electrode 3 is also reduced. Consequently, in the photovoltaic module 1, the resistance value between the transparent electrode 3 and the photoelectric conversion layer 4 is reduced, allowing for a high photoconfinement effect and improved conversion efficiency.

[0097] According to the photovoltaic module 1 of at least one embodiment described above, it is possible to suppress variations in quality and obtain a high light confinement effect.

[0098] Although several embodiments and modifications of the present invention have been described above, these embodiments and modifications are merely examples and do not limit the invention as defined in the claims. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, not all combinations of features described in these embodiments and modifications are necessarily essential for solving the problem of the invention. Moreover, these embodiments and modifications are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents. [Explanation of Symbols]

[0099] 1...Photovoltaic module, 2...Substrate unit, 3...Transparent electrode, 4...Photoelectric conversion layer, 5...Upper electrode, 9...Light, 20...Substrate, 21...Filling section, 22...Upper substrate, 30...Transparent conductive film, 31...Transparent electrode film, 200...Front surface, 201...Back surface, 202...Reference plane, 203...Peak, 203a...Vertex, 204...Valley, 204a...Bottom point, 205...Rump, 206...Ridge, 206a...Ridge line, 206b...Ridge line, 207...Endpoint, 210...Surface, 211...Particle, 220...Surface, 300...Surface, 301...Back surface, 302...Reference plane, 303...Electrode peak, 303a...Vertex, 304...Electrode valley, 304a...Bottom point, 305...Electrode uneven surface, 306...Ridge line, 306a...Ridge line, 306b...Ridge line, 307...Endpoint, 310...Surface

Claims

1. A substrate having an uneven surface consisting of multiple peaks and multiple valleys, and a light-transmitting substrate unit having a filling portion that fills the uneven surface so that the surface becomes flat, A transparent electrode that transmits light is provided on the substrate unit, A photovoltaic module equipped with this module.

2. The substrate unit has an upper substrate placed on the filling portion, The transparent electrode is provided on the upper substrate, The photovoltaic module according to claim 1.

3. The transparent electrode consists of a transparent conductive film and a transparent electrode film. The transparent conductive film has an electrode uneven portion consisting of a plurality of electrode peaks and a plurality of electrode valleys. The photovoltaic module according to claim 2.

4. The filling portion adheres the substrate and the upper substrate. The photovoltaic module according to claim 2.

5. The filling portion is composed of a plurality of transparent particles, The photovoltaic module according to claim 1.

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